不同含水量下工具材料切向土壤黏附特性（摘选）

为了提高越野车辆性能和建筑、农业领域机械工作效率,就需要了解土壤黏附机理。该试验旨在找到不同工具材料的土壤切向黏附与含水率之间的关系,探讨土壤切向黏附对土壤剪切力学性能的影响。试验对橡胶（RUB）、钢（SS400）和树脂（PEEK）3种材料进行了直剪试验。结果表明,土壤和材料之间的切向黏附随着土壤含水量的增加而增加至最大值后降低。土壤切向黏附最大值的排序是钢（SS400）,其次是橡胶（RUB）,最后是树脂（PEEK）。结果还表明,3种材料道具与测试土壤间的外摩擦角随着土壤含水率的增加先降低后增加,当发生剪切的时候,随着剪切的发生,土壤含水量导致切向黏附的变化进而直接影响剪切应力和外摩擦角。      

Isolation and characterization of some antioxidative compounds from the rhizomes of smaller galanga (Alpinia officinarum Hance)

Antioxidative compounds were isolated from the methanol extract of fresh rhizome of smaller galanga (Alpinia officinarum Hance). Seven phenylpropanoids (1-7) were finally obtained by reversed-phase HPLC, and their structures were elucidated by MS and NMR analyses. They comprised the two known compounds, (E)-p-coumaryl alcohol gamma-O-methyl ether (1) and (E)-p-coumaryl alcohol (6), and the five novel compounds, stereoisomers of (4E)-1,5-bis(4-hydroxyphenyl)-1-methoxy-2-(methoxymethyl)-4-pentene (2a and 2b), stereoisomers of (4E)-1,5-bis(4-hydroxyphenyl)-1-ethoxy-2-(methoxymethyl)-4-pentene (3a and 3b), (4E)-1,5-bis(4-hydroxyphenyl)-1-[(2E)-3-(4-acetoxyphenyl)-2-propenoxy]-2-(methoxymethyl)-4-pentene (4), (4E)-1,5-bis(4-hydroxyphenyl)-2-(methoxymethyl)-4-penten-1-ol (5), and (4E)-1,5-bis(4-hydroxyphenyl)-2-(hydroxymethyl)-4-penten-1-ol (7). Compounds 1-7 were detected for the first time as constituents of galanga rhizomes and exhibited antioxidative activities against the autoxidation of methyl linoleate in bulk phase.     

Investigation of the prevalence of neurologic equine herpes virus type 1 (EHV-1) in a 23-year retrospective analysis (1984–2007)

A single nucleotide polymorphism in the equine herpesvirus 1 (EHV-1) DNA polymerase gene (ORF30 A₂₂₅₄ to G) has been associated with clinical signs of equine herpes myeloencephalopathy (EHM). The purpose of our study was to determine the odds ratio for this genetic marker and EHM using a panel of field isolates from North America collected over the past twenty-three years. EHV-1 isolates cultured at the Cornell University Animal Health Diagnostic Laboratory from 1984 to 2007 were retrieved along with their clinical histories. DNA was extracted from these EHV-1 cultures and allelic discrimination was performed using real-time PCR. The results were confirmed by sequencing of the target region in ORF30. PCR and sequencing were in 100% agreement and showed that 19 out of the 176 isolates had the ORF30 G₂₂₅₄ allele (11%), of which16 were EHM cases and 3 respiratory or abortion cases. The odds of having neurologic disease with the ORF30 G₂₂₅₄ genotype were computed as 162 times greater than those with the opposite allele ORF30 A₂₂₅₄ (95% confidence interval: 35–742). Despite this strong statistical significance, 24% (5/21) of horses with neurologic disease in our study population harbored the “non-neurologic” form of the allele (ORF30 A₂₂₅₄), suggesting that other factors may also contribute to the onset of EHM.     

Identification of oyster-derived hypotensive peptide acting as angiotensin-I-converting enzyme inhibitor

Angiotensin-I-converting enzyme (ACE) plays a crucial role in the crisis of hypertension. Some peptides that originate from protease hydrolysates are known to suppress ACE activity in vitro and in vivo. Here, we investigated whether trypsin hydrolysate of oyster Crassostrea gigas showed hypotensive activity and ACE inhibition. The hydrolysate significantly suppressed systolic blood pressure and ACE activity in spontaneously hypertensive rats following a one-shot oral administration and a long-term feeding experiment lasting 9 weeks. Each hydrolysate from oyster tissue showed ACE inhibitory activity, indicating the hypotensive effect was due to synergism. One potent ACE inhibitory peptide, Asp-Leu-Thr-Asp-Tyr, was identified from the hydrolysate of the striate muscle, and the peptide exhibited hypotensive activity in vivo. Protease digestion analysis suggested that Asp-Tyr could be the real effector of this penta-peptide in vivo.     

Effects of medium‐chain fatty acid‐cyclodextrin complexes on ruminal methane production in vitro

The purpose of the present study was to evaluate effects of medium‐chain fatty acid‐cyclodextrin (CD) complexes on ruminal methane and volatile fatty acid production, and protozoal activity in vitro. Medium‐chain fatty acid‐CDs used in this study were caprylic acid (C8)‐αCD or ‐βCD, capric acid (C10)‐αCD or ‐βCD, and lauric acid (C12)‐αCD or ‐βCD. A 60‐mL of diluted rumen fluid was incubated anaerobically at 38°C for 6 h with the addition of the complex (10–40 mg as fatty acid). Each of the fatty acid‐CDs reduced the number of protozoa, with the order C10 > C12 > C8, and βCD complexes were more effective than αCD complexes. Molar proportions of acetic acid remained unchanged with the addition of fatty acid‐CD, while that of propionic acid increased, being significant for C8‐αCD and βCD, and C10‐αCD and βCD (P < 0.05). Hydrogen production decreased by about 70% of control with the addition of 40 mg of C8 and C10‐CD, on the other hand, it tended to increase with the addition of C12‐CD in both αCD and βCD. Methane production decreased by about 20% with the addition of 40 mg of complexes, except for C10‐βCD, which significantly reduced methane production by about 60%. In conclusion, the addition of C8 or C10‐CD to ruminant diets may be effective in reducing methane production.     

Occurrence of intraportally-infused urea-15N in the urine of domestic fowl.

1. Measurements were made in situ to determine the occurrence of intraportally infused urea-15N in ureteral urine of the fowl. 2. Of the total amount of infused urea-15N, 15% was excreted intact into the urine (90% of urinary total 15N) whereas 9% remained unchanged in the blood (78% of blood non-protein-15N). 3. The proportions of non-protein-15N in the blood, liver and kidney were 12, 3 and 1%, respectively of the infused 15N. Protein-15N was 3% of that infused in blood and much less in liver and kidney. 4. About 1% of the infused 15N was observed in the urinary uric acid, and 3% of the infused 15N in non-protein N, other than urea, ammonia and glutamine amide N, of blood and liver. 5. No appreciable amounts of 15N were present in ammonia and glutamine amide N of blood, liver or kidney and in uric acid of liver or kidney. 6. The caecal contents contained about 1% of the infused 15N with 15% of this as ammonia-15N. 7. It is concluded that intraportal urea is mostly excreted unchanged into ureteral urine of the fowl.     

Changes in blastogenic responses of lymphocytes and delayed type hypersensitivity responses after vaccination in dogs.

To clarify the immunologic effects of vaccination in dogs, we monitored total leukocyte and lymphocyte counts, humoral antibody responses, blastogenic responses of lymphocyte, and delayed type hypersensitivity (DTH) responses after vaccination. Mixed vaccines were administered on day 0 except for canine parvovirus (CPV) vaccine which was readministered on day 21. The puppy and adult dogs had a significant decrease in leukocyte and lymphocyte counts on day 7. The puppies showed a significant increase in the blastogenesis of lymphocytes after each vaccination, whereas the adult dogs had no significant changes. However, the adult dogs were divided into two groups, high responders and low responders in blastogenesis of lymphocytes. The dogs with higher or lower response in SI values on day 0 tended to show decrease or increase after the first vaccination, respectively. Since almost all dogs developed high titers of humoral antibody, it is considered that vaccination acts in an immunomodulative fashion. DTH responses to phytohemagglutinin (PHA) and CPV vaccine monitored at 0, 3, and 8 weeks after the first vaccination produced strong reactions, in particular those to CPV vaccine rose significantly after vaccination and maintained the higher responses for at least 2 months. These results suggest that DTH responses to PHA and CPV vaccine are helpful to monitoring non-specific and specific immune functions in vivo, therefore, DTH could be used as simple and rapid immunologic tests in canine practice.     

Salt effects on transplant mortality,growth and rubber yields of guayule

Summary Because of the strategic and industrial importance of natural rubber, there has been renewed interest in cultivating guayule (Parthenium argentatum). This study was performed for assessing feasibility of guayule cultivation with waters high in dissolved salts. The test materials included six USDA selections (11591, 11605, 11619, 11646, 12229 and N576), one cultivar (593) and one hybrid (4265XF). Seedlings were grown for l0 weeks in a greenhouse and transplanted in the spring and in the summer into lysimeters (unit surface dimension of 6 x 7 m) containing loamy sand or silt loam. They were grown with simulated irrigation waters having four levels of salinity (0.8, 2.4, 4.6 and 7.2 dSm^–1 with SAR < 13) and an additional water containing 5 mmol L^–1 of Mg at 2.4 dSm^–1. In the spring planting, over 90% of the transplants survived when furrow irrigated weekly with waters of 4.6 dSm^–1 or less. However, transplant growth for the first several months was reduced by half at irrigation water salinity of 4.6 dSm^–1. In the summer planting, several fold increases in mortality and growth reduction occurred. Dry top Shrub yields after the two growing seasons following the spring planting averaged 10 Mg ha^–1 at 0.8 dSm^–1 and declined on the average 15 and 51 % when irrigated with waters of 4.6 and 7.2 dSm^–1 respectively. The amount of water used to produce one ton of dry shrub was 1,600 m³ with waters of 0.8 and 4.6 dSm^–1, and 1,900 m³ with water of 7.2 dSm^–1. The contents of rubber in the shrubs averaged 61 g kg^–1 at 0.8 dSm^–1 and increased to 70 g kg^–1 at 7.2 dSm^–1. whereas resin contents were not affected by the salt treatments. Resulting rubber yields were reduced on the average by 8.5 and 44% at 4.6 and 7.2 dSm^–1. respectively, because of the reduction in shrub yields. Selection N576 produced the largest rubber yields with the highest rubber content at all levels of salinity. Increasing Mg concentrations from 0.5 to 5 mmol L^–1 in the irrigation waters reduced neither yields nor transplant survival. Yield reductions observed here appeared to be related to Na, but not Mg.Contribution from Texas Agricultural Experiment Station. Supported in part by a grant from the Latex Commission, USDA and by the US-Israel Binational Agricultural Research and Development (BARD) fund     

Cloning of swine desmoglein 1 and its direct proteolysis by Staphylococcus hyicus exfoliative toxins isolated from pigs with exudative epidermitis

Exudative epidermitis (EE) is an acute, often fatal skin disease of piglets caused by Staphylococcus hyicus. Clinical and histopathological manifestations of EE are similar to those of staphylococcal scalded skin syndrome (SSSS), a human blistering skin disease, in which exfoliative toxins produced by Staphylococcus aureus digest the extracellular domains of desmoglein (Dsg) 1 and cause loss of epidermal cell-cell adhesion. The aims of this study were to isolate and characterize cDNA for full length of swine Dsg1, and to determine whether the extracellular domains of swine Dsg1 produced by baculovirus (sDsg1-His) could be digested by four isoforms of exfoliative toxin produced by S. hyicus (ExhA, ExhB, ExhC and ExhD). Nucleotide sequencing revealed that swine Dsg1 cDNA consisted of an open reading frame of 3138 bp, encoding a precursor protein of 1045 amino acids. Deduced amino acid sequence of the swine Dsg1 precursor were highly homologous to corresponding bovine, canine, human and murine sequences. Immunoadsorption assay with a secreted form of sDsg1-His revealed that sDsg1-His specifically absorbs the immunoreactivity of 10 human pemphigus foliaceus sera against swine keratinocyte cell surfaces, suggesting its proper conformation. When sDsg1-His was incubated in vitro with Exhs, all four isoforms of Exh directly digested sDsg1-His into smaller peptides, whereas removal of calcium from sDsg1-His completely inhibited its proteolysis by these four Exhs. Recognition and digestion of calcium-stabilized structure on the extracellular domains of swine Dsg1 by Exhs indicated that EE shares similar molecular pathophysiological mechanisms of intra-epidermal splitting with SSSS in humans.